Adjustable throttle valve stop



N A M E N H. E

ADJUSTABLE THROTTLE VALVE STP Filed June 2o,l 1959 ATTORNEY Patented Nov. ,7,1939

UNITED STATES PATENT OFFICE f l M aivasso ADJUSTABLE rHRo'rrLE VALVE s'roP f Ernst Il. Nieman,` NormandyQMo., assigner to v Carter Carburetor Corporation, St. Louis, Mo.,

a corporation of Delaware t Application June20, 1939, Serial No. 280,111

4 Claims.

f This inventionl relates to means providing an adjustable limit to the movement of throttle valves as used in connectionwith internal combustion engine carburetors and more particularly 5 to the provision of a controlled frictional detention for said adjustable limit or stop.

The provision of an adjustable `stop tolimit the closing of a carburetor throttle valve for the purpose of `obtaining the desired idling speed is well known and understood. Threaded means for theadjustment of suchv stops is most commonly used and usually comprises a screw threadedly engaged in the throttle valve operating lever and fadaptedto contact an abutment on the carburetor l5 body. The use ofl threadedv adjustment means,

however, presents the problem of holding the adjustment screw in any predetermined position against the forcesV of motor vibration and substantial impacts occasioned by sudden throttle clos- '20 ing lmovements which tend to alter the Iadjust-v `ment."-.This problem has usually been solved by the inclusion of aspring arranged in such manner astoA set up frictional resistance of the movement of the adjustment screw. Itis an object of this invention to provide a novel meansv of f producing stress between thethreads of a threaded member and the threads of an engaging screw.

It is a further object of this invention` to provide a throttle valve operating lever having two.

definitely spaced and parallel portionsthereof drilled and threaded in alignment and tted with an adjustment screw of similar pitch diameter but of different pitch than the internal threads. Other objects and advantages will appear in the following description and accompanying drawing in which:

Fig. 1 of the drawing indicates the flange end ol.' a conventionalY carburetor embodying one form 40 of my invention.

Fig. 2 is a view taken on line 2--2 of Fig. l. Fig. 3 is an enlarged fragmentary view of the throttle valve operating lever with parts shown in section for clearer illustration.

' 45 Numeral I indicatesa portion of'a conventional for remote operation of the lever I may include the rod IE.

`eause'the high point of the external thread to .valve 3` It will be understood that the fit between theexternal threads ons`crew I2 and the internal threads in tangs B and 9, necessary to permit 10 large volume economical production, would also permit the rotation and alteration of any predetermined adjustment of screw I2 under incessant motor vibration or impacts against the abutment I3. I in order to produce a stress between the 15 threads of screw I2 and members 8 and 9 and thereby set up a frictional resistance to rotation,

I have provided a screw having similar pitch diameter to the internal threads in tangs 8 and 9 but having a slightly different pitch or lead. Re- 2o ferring to Fig. 3; in this illustration AIv have chosen to select a slightly shorter pitch for the external thread I4 than that ofthe internal thread I5 and I5q. in the order of, say 26 threads per inch for the external thread I4 and 24 threads per inch for 25 the internal thread I5 and I5a. Further, I have selected a dimension between the inner surfaces Ba and 9a whchis not an even multiple common to both pitchesbut is, however, proportioned to G approximately. coincide with the root of the internal thread in 9a as the screw is advanced thereinto. AS the screw I2 is rotated clockwise from the position shown in full lines in Fig. 3. to the position shown in dotted lines, deiiection of one or both of members 8 and B must take place as indicated by dotted lines to accommodate this mis-matching of threads and will, thereby, impose a constant stress upon the screw thread sur faces in engagement.

It will be understood that in this rncdication the internal threads in both Ii and 9 are formed in one direction with a single tap. Also that as the dimension between surfaces Ba and Qavaries from a common multiple of both pitches the stress set up will increase and the stress may, thereby, be proportioned. Upon considering the compare.-

tively few-internal threads in either of tangs il or 9 and the comparatively free iit ci the threads it 5G will be seen that the accumulated difference in pitch in the thickness oi either tang is not surticient to cause undue distortion of the threads. It is intended that the drawing and preceding description `be illustrative and not limiting and 55 that the inventor contemplates the exclusive use of all modiiications which come within the scope of the following claims.

I claim:

1. The combination of a screw and a plurality of yieldably connected members perforated and internally threaded in alignment and engaging said screw, the threads of said screw being of different pitch than said internal threads, and said members being spaced to a dimension which varies to some degree from a common multiple of both pitches thereby requiring relative movement of said members for the engagement of said screw.

2. The combination of an oscillating lever, an adjustable stop for said lever, and threaded means for positioning said adjustable stop, comprising a screw, and a plurality of yieldably connected members, said members being perforated and internally threaded in alignment and engaging said screw, the threads of said screw being of different pitch than said internal threads, and said members being spaced to a dimension which varies to some degree from a common multiple of both pitches, thereby requiring relative movement of said members for the engagement of said screw.

3. In combination an internally screw threaded member, a second internally screw threaded member resiliently connected therewith, the threads of said members being substantially coaxial and of the same size and pitch, and a screw mounted in said threaded members, said screw being threaded with threads of a slightly different pitch, whereby said screw is frictionally held in position by the resiliency of the connection between said members.

4. For use with an internal combustion engine carburetor, a throttle valve operating lever, comprising a stamping having a plurality of formed and internally screw threaded portions, said internal threads in said formed members being coaxial and of the same pitch diameter and pitch, and an adjustment screw threadedly engaged in said formed portions, said screw'being threaded with threads of similar pitch diameter but of slightly different pitch than said internal threads, whereby said screw is frictionally held in position by the resiliency of said formed members.

ERNST H. NIEMAN. 

